0Raptor: the open, electric monocycle

When cities think about environmentally-safe modes of personal transportation, thoughts usually turn to electric solutions. But remember the Segway? Introduced 10 years ago, this electric stand-up "bicycle" was intended to have major mass diffusion, but that never happened, perhaps because of its steep price tag (7500 euros for the base model in Italy) and also to road-access issues (is it like a bike? a pedestrian? a car?). Similar vehicles by Toyota and Honda have also had limited sales.

Could an "Open Segway" be the solution to the diffusion of electric alternatives to personal transportation? It's hard to say, but being open would lower costs and thus change the rules of the game. One example that's working in this direction is the Raptor, constructed by Nick Thatcker using Arduino. Structurally, the Raptor is essentially a monocycle - you ride it like a motorcyle but it has just one wheel, and uses Segway-like balancing technology (before the Rapter, Thatcker built a Segway knock-off called NoWay...).

An Arduino Uno module is at the heart of the Raptor and serves to receive signals about the monocycle's movement and thus indicate to the motor how much power to give to acceleration or braking, functions that, as in the Segway, depend on the angle of the rider. Adding to this module, Thatcker used an Sparkfun Inertial Measurement Unit (IMU) - essentially a combination of an accelerometer and a gyroscope - to measure direction, position and speed, while the motor is a SyRen 25A driver.

That's all for the insides. The body is in PVC and polycarbonate and holds a 350 Watt, 24 volt electric motor and its batteries. The single wheel was purchased on eBay and is connected to the motor by a simple bike chain. Altogether the Raptor weighs 25 kilos and travels at about 15km/h for about 1.5 to 2 hours.

Adding up the cost of the components you can approximate that the total cost for this device is a fraction of that of the Segway: the electrics (Arduino Uno, SyRen 25A, IMU SparkFun) add up to 150 euros or so, plus a lot of patience and manual labour to assemble it.